Abstract: An article for use in producing silica optical fibers doped with a metal de obtained by synthesis from low pressure vapor reactants is made from an outer supporting tube extending along a longitudinal axis and having first and second longitudinally opposite ends and an inner surface on which silica and a dopant formed by a reaction between vapor-state reactants can be deposited over a longitudinally extending silica-deposition zone. Respective first and second joints engage the ends of the supporting tube and each have a fixed part and a rotating part. Each rotating part supports the respective end for rotation relative to the respective fixed part about the axis. At least one of the reactants is introduced into the supporting tube through the first joint and depleted gases are discharged through the second joint.